Drill



Feb. 21, 1967 K.-H. A. E. FABER DRILL 4 Sheets-Sheet 1 Filed Dec. 11, 1964 Fig.5

0 vii/Ill 9' Feb. 21, 1967 K. H. A. E. FABER DRILL 4 Sheets-Sheet 2 Filed Dec. 11, 1964 K. H. A. E. FABER Feb. 21, 1967 DRILL 4 Sheets-Sheet 5 Filed Dec. 11, 1964 Feb.v 21, 1967 H. A. E. FABE-R DRILL 4 Sheets-Sheet 4 Filed Dec. 11, 1964 i United States Patent Office 3,304,815 Patented Feb. 21, 1967 3,304,815 DRILL Kurt Heinrich Albert Erich Faber, Sandviken, Sweden,

assignor to Sandvikens Jernverks Aktiebolag, Sandviken, Sweden, a corporation of Sweden Filed Dec. 11, 1964, Ser. No. 417,538

Claims priority, application Sweden, Dec. 14, 1963,

8 Claims. (Cl. 77-68) The present invention relates to a drill having means for supplying a flushing medium to the front of the drill. The purpose of such flushing medium is to cool and lubricate the drill and also to remove the cuttings. The invention has been found especially useful in metal drills with a tubular drill stem, the chips formed during the drilling being removed through said stem.

In previously known drills the flushing medium has been supplied through openings or nozzles in the forward direction of the drill. Said medium has been returned by the contact with the bottom of the drill hole, the only force for bringing the medium rearwardly being the reaction force from the bottom of the hole when the forward flow reaches said bottom. This causes a pressure at the bottom of the hole and a tendency for leakage of flushing medium between the drill and the wall of the drill hole. Another disadvantage is that the rearward flow often is too weak" to secure the desirable efiiciency in removing the cuttings, i.e. chips in the case of metal drills.

' A purpose of the present invention is to provide a separate rearward action'on the return flow of the'fiushing medium thereby lessening the pressure of said medium at the front of the drill and also lessening the tendency of leakage. In thisway it becomes unnecessary to use special gaskets for preventing the leakage. Said separate rearward action also improves the removal of cuttings.

The separate rearward action according to the invention is obtained by diverting a part of the flow of flushing medium before it reaches the front of the drill and guiding'the diverted part rearwardly by means of nozzles or the like, thereby obtaining a rearward ejector effect. The rest of the flow, which continues to the front of the drill, is, on its return, mixed with the said diverted part and flows rearwardly therewith, the momentum of the diverted flow being imparted to the mixture, so that the whole 'flowhas a homogenous rearward momentum. When the force for obtaining the rearward momentum is provided in this way by separate means it is obvious that the pressure of the flushing medium at the front of the drill may be smaller, thus diminishing the tendency for leakage. The strength of the diverted flow of medium can be increased without increasing the said pressure at the front, thus providing the desired rearward force of the flow for obtaining sufficient removal of the cuttings.

In the present specification the word forward relates to the axial penetration direction of the drill, the word rearward relating to the opposite direction.

Details of the construction and of the purposes of the invention appear from the following specification and the accompanying drawings in which:

FIG. 1 is partly a longitudinal section and partly an elevation of a tubular drill with a double wall according to the invention, FIG. 2 is a longitudinal section of a modification of the encircled part of the drill in FIG. 1,

FIG. 3 is a longitudinal section of another modification of the encircled part of the drill in FIG. 1,

FIG. 4 is a cross section on the line 44 in FIG. 1,

FIG. 5 is a fragmentary longitudinal section of another modification of the drill in FIG. 1,

FIG. 6 is partly a longitudinal section and elevation of a second embodiment of the drill,

FIG. 7 is a cross section on the line 7-7 in FIG. 6,

FIG. 8 is a longitudinal section of a third embodiment of a drill according to the invention,

FIG. 9 is a side elevational view of the drill in FIG. 8,

FIG. 10 is an enlarged cross section on the line 1010 in FIG. 8,

FIG. 11 is a fragmentary longitudinal section of a modified detail of the drill in FIG. 1,

- FIG. 12 is a fragmentary longitudinal section of another modification of the same detail that is shown in FIG. 11.

In FIG. 1 is shown a drill acting on a work piece 100. The drill stem comprises a sleeve 10 and a tube 11, which at its fore end carries the drill bit 12 which advantageously may be of the type disclosed in my application Ser. No. 271,054, filed April 8, 1963, and now abandoned. The front end of the drill bit has a number of cutting inserts 13. Concentric with the tube 11 there is an inner tube 14 having a thinner wall than the outer tube, and there is an annular space 15 between the tubes. The rear end of the inner tube 14 abuts tightly against the sleeve 10. An annular outer sleeve 16 surrounding the sleeve 10 has a hole 17 for supplying flushing medium to the drill. The outer sleeve 16 has at its inside an annular recess 18 which on both sides is surrounded by packings 19 and 20. Thesleeve 10 has an opening 21 connecting the recess 18 with the rear part of the space 15. The described device permits rotation of the 'drill within the sleeve 16, at the same time as a flushing medium is continuously supplied through the hole 17 to the space 15 as indicated by' the arrow 28.

The fore part of the'inner tube 14 abuts against the flat portion of a ring 22 of relatively thin sheet material, said ring having a rearwardly inclined flange 22a extending rearwardly within the tube 14. The foremost part of the Wall of the tube 14 has openings 23 separated by forwardly protruding portions 24 of the wall. The portions 24 abut against the ring 22, the openings 23 forming slits along the ring. There are bores 26 in the wall of the drill bit. These bores 26 are surrounded by a flange 27 protruding from the outer tube 11 coaxially with the drill axis 25.

The flushing medium is supplied at the rear end of the space 15 as indicated by the arrow 28. When the flow of medium reaches the fore end of the space 15 it is divided into two branches as indicated by the arrow 29 having two branches 29a and 2912. A part of the flow indicated by arrow branch 29a passes through the openings 23 and is deflected rearwardly by the flange 22a on the ring 22. The rest of the flow indicated by arrow branch 2% flows through bores 26 and is directed by the flange 27 forwardly to the cutting inserts and cutting edges, as indicated by the arrows 30. The flow along the arrows 30 returns rearwardly from the bottom of the drill hole inside the drill and joins the flow ejected rearwardly at the ring 22. In this way the total rearward flow is improved by the ejection effect of the diverted flow along the arrow 29a. The rearward action of the diverted flow lessens the pressure of the flushing medium at the front of the drill and consequently lessens the tendency for leakage between the drill and the wall of the hole. Said rearward action also improves the chip removal along the inside of the drill.

The flushing medium flows along the inside of the drill to a rear part of the drill where it is passed to the outside for instance through a sleeve device (not shown) similar to the medium supply structure 16-20. After separating the chips from the flushing medium, the medium can be recirculated through the drill.

partly an The flushing medium serves for lubricating, cooling and chip removal. Dependent upon which of these purposes is predominant and possibly other factors determined by the quality of the work piece, different flushing media can be used. Sometimes a liquid is suitable, as for instance oil. It is also possible to use water containing an emulsion of some lubricant. If a liquid is used it is preferable that it fills the circulation system, the internal tube 14 thus being filled by the liquid. In some cases a gas is suitable as flushing medium. When for instance drilling cast iron the flushing medium can be air carrying a mist of lubricant.

FIGS. 2, 3, l1 and 12 show various embodiments of the device for obtaining the rearward ejection effect, FIGS. 11 and 12 being variations of FIG. 3. In FIG. 2 a rearward flange 31 integral with the drill bit 12a guides the medium flow as indicated by the arrows in the same way as the flange 22a of the ring 22 in FIG. 1. In FIG. 3 the rearward flow is obtained by aid of one or more rearwardly inclined holes or slits 32 in the tube 140.

According to FIG. 11 which is a modification of FIG. 3 the internal tube corresponding to the tube 14 of FIG. 1 is divided into two parts marked 141 and 142. The adjacent ends of the parts 141 and 142 are slightly conical along portions 143 and 144, between which there is an annular slit 145. At intervals the outer conical portion 143 is closer to the axis as shown in the right hand part of the figure, forming contact points 146 between the portions 143 and 144. There should be at least three such contact points, and the portions 143 and 144 are suitably brazed or welded together at said contact points.

FIG. 12, which is another variation of FIG. 3, shows the fore end of the internal tube, here marked 147, on a larger scale than in the previous figures. In front of the tube there is a short tubular ring 143 which has the same diameter as :the tube 147. The adjacent ends of the tube 147 and the ring 148 are chamfered and placed at a distance from each other to form a slit 149 which is inclined inwardly and rearwardly. In order to hold the tube 147 and the ring 148 in the desired position a sleeve 150 is mounted around them. This sleeve 150 has its end edges 151 and 152 somewhat countersunk in shallow annular recesses around the tube 147 and the ring 148 to form an abutment determining the distance between the tube and the ring and the consequent width of the slit 4 149. In the sleeve 150 there are holes 153 for the passage of flushing medium. The sleeve is suitably brazed to the tube and the ring.

It is important that the sides of the slits shown in FIGS.

'3, 11 and 12 somewhat overlap each other in the direction of the slit in order to obtain the proper guidance of the flow of the medium. The inclination of the slit in relation to the drill axis should preferably be within the range -45 C. In order to avoid turbulence of the flow the inclination can advantageously be 8-15 The openings should be distributed as evenly as possible around the circumference of the tube in order to have a homogeneous and even flow.

For improving the ejector effect, especially in long drills, one or more extra ejector devices may be provided along the drill. FIG. 5 illustrates how the inner tube corresponding to the tube 14 of FIG. 1 is divided into two parts 14a and 1411, the adjacent ends being beveled and placed with a rearwardly and inwardly directed slit 533 between them. The parts 14a and 14b can be joined by spot welding or brazing at spaced intervals around the periphery, leaving slits between the joined spots for the flow of flushing medium. Said flow is divided into two parts, one 34a passing from the slit 33 rearwardly into the tube, the other 34b continuing forwardly towards the fore part of the drill. The device in FIG. 5 can be modified in the way shown in FIG. 12.

The drill in FIG. 1 has a thick outer tube 11 which is advantageous for obtaining the greatest possible moment inertia of the drill d m lle t possible stress in the 4 material. Sometimes it is advantageous to have a thick inner wall and thin outer wall as shown in FIG. 6. The thin outer tube 40 is placed around the thick inner tube 41 with a narrow space 42 between the tubes. Flushing medium is supplied to the space 42 through the connection 43. In this case the connection 43 is firmly attached to the drill, which means that the drill does not rotate but the work-piece 101 rotates. It is of course possible as an alternative to use the rotatable connection 1620 shown in FIG. 1 on the drill of FIG. 6 or the stationary connection shown in FIG. 6 on the drill shown in FIG. 1.

The outer tube 40 of FIG. 6 extends to the drill bit 52 and passes at its fore end a ring of radial holes 44 through the wall of the drill bit. These holes are connected to openings 45 through the fore end of the inner tube 41. The openings 45 are separated by lugs 46 (FIG. 7) which are integral with the tube 41. The lugs 46 abut against an annular ring 47 similar to the ring 22 of FIG. 1, having the internal edge rearwardly bent. The ring 47 rests against the drill bit 52.

When the flow of flushing medium, supplied at the connection 43 and indicated by the arrow 48, reaches the fore end of the space 42, a part of the flow is diverted along the arrow 49a, the rest of the flow continuing forwardly along :the arrow 4%. The diverted part of the flow goes through the holes 44, 45 and is deflected rearwardly by the ring 47. The rest of the flow goes up to the bottom of the drill hole and returns as indicated by the arrows 50, whereafter it joins the rearward flow from the ring 47. In this way the same ejector effect is obtained as above described in connection with FIG. 1.

FIGS. 8-10 show a so-called gun drill comprising a tubular part and a drill bit 61. As appears from FIG. 10 the tubular part has a cross section which is partly inwardly deflected to a V-shaped groove 62. The drill bit has a corresponding groove. The chips are removed along the groove 62. In the bottom of the groove a lug shaped portion 63 is cut out in the wall of the tube and bent inwardly, thereby forming an opening 64 facing rearwardly. Flushing medium is supplied in the direction indicated by the arrow 65 and the flow is divided at the opening 64 into a rearwardly directed flow 65a through the wall of the V-shaped recess and a forwardly directed flow 6517, which passes through a bore in the drill bit 61 to the cutting edges. The ejector effect of the flow along the arrow 65a as well as the flow returning from the cutting edges carry the chips. There can be additional openings along the drill with ejector effect as indicated by broken lines at 66.

The invention is illustrated in connection with a metal drill which represents an important field of use for the invention, but it can also be employed in connection with other kinds of drills as for instance tubular rock and earth drills.

I claim:

1. A drill for chip cutting piece comprising a tubular shaft having an inner and an outer wall with a space therebetween, cutting edges on the front end of said shaft, at least one of said cutting edges extending laterally beyond the outer surface of said tubular shaft, means for delivering flushing medium to said space, a first aperture having its outlet at the outer surface of said outer wall rearwardly of said cutting edges for delivering a forwardly directed first flow of flushing medium from said space to said cutting edges, a passageway permitting return flow of flushing medium from said cutting edges to the cavity within said inner wall and a second aperture having its outlet at the inner surface of said inner wall for delivering a second flow in the form of a rearwardly directed jet of flushing medium from said space int-o said cavity.

2. Drill according to claim 1 in which the rearward direction of the second flow is obtained by means of a flange around the periphery of the inner wall adapted to deflect the flow from the second aperture rearwardly,

drilling of a metal work- 6.?) the second aperture comprising a number of openings spaced around the periphery of the inner wall.

3. Drill according to claim 1 in which the rearward direction of the second flow is obtained by means of a rearward direction of the second aperture.

4. Drill according to claim 3 in which the second aperture consists of a number of openings surrounding the inner cavity of the drill shaft.

5. Drill according to claim 3 in which the second aperture substantially has the shape of an annular slit around the periphery of the inner wall, said slit being subdivided and forming a number of arcuate slits.

6. Drill according to claim 1 in which the first aperture has the shape of a number of openings around the periphery of the outer wall of the drill shaft, a flange surrounding said openings for deflecting the flow forwardly on the outside of the drill.

7. Drill according to claim 1 in which the jet effect of the second fiow is sufficiently strong to prevent leakage outwardly of the first flow between the outside of the drill and the wall of the drilled hole.

8. Drill according to claim 1 in which a third aperture is arranged in the inner wall to the rear of the second aperture for obtaining a third, rearwardly directed flow cooperating with and increasing the rearward jet effect of the second flow.

References Cited by the Examiner UNITED STATES PATENTS 1,281,420 10/1918 Reid 77-68 FRANCIS S. HUSAR, Primary Examiner. 

1. A DRILL FOR CHIP CUTTING DRILLING OF A METAL WORKPIECE COMPRISING A TUBULAR SHAFT HAVING AN INNER AND AN OUTER WALL WITH A SPACE THEREBETWEEN, CUTTING EDGES ON THE FRONT END OF SAID SHAFT, AT LEAST ONE OF SAID CUTTING EDGES EXTENDING LATERALLY BEYOND THE OUTER SURFACE OF SAID TUBULAR SHAFT, MEANS FOR DELIVERING FLUSHING MEDIUM TO SAID SPACE, A FIRST APERTURE HAVING ITS OUTLET AT THE OUTER SURFACE OF SAID OUTER WALL REARWARDLY OF SAID CUTTING EDGES FOR DELIVERING A FORWARDLY DIRECTED FIRST FLOW OF FLUSHING MEDIUM FROM SAID SPACE TO SAID CUTTING EDGES, A PASSAGEWAY PERMITTING RETURN FLOW OF FLUSHING MEDIUM FROM SAID CUTTING EDGES TO THE CAVITY WITHIN SAID INNER WALL 